Step 5:
Set up a double boiler and melt the chopped chocolate and butter together. Whisk the mixture while it melts to ensure it blends smoothly.

Step 6:
Set an electric mixer to high speed and whisk together the sugar, the vanilla extract, the two whole eggs, and the two egg yolks. Mix until the mixture is thick and light (about five minutes).

Step 7:
Fold the melted chocolate and flour into the mixture until it’s just combined.

Step 8:
Spoon the mixture into the custard cups/ramekins and pop one of the chocolate balls into the middle of each one.

Step 9:
Bake the cakes for fifteen minutes (or until firm to the touch).

Step 10:
Remove the cakes from the oven and let them cool for five minutes. Take a knife and run it around the inside of the ramekin/custard cup, flip the cup onto a plate, and the cake should fall out. Serve and enjoy!